Method of fabricating high performance BiCMOS structures having poly emitters and silicided bases
AssigneeFairchild Semiconductor Corporation
InventorsPrateep Tuntasood, Juliana Manoliu
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Abstract
A process is disclosed for simultaneously fabricating bipolar and complementary field effect transistors. The process enables distinguishing the bipolar devices from the CMOS devices with a single base mask 108, while requiring only a single additional mask 114 to define the bipolar emitter and MOS gates. The process forms the gate oxide 100 for the MOS devices at an early stage, then protects that oxide with polysilicon 103 during subsequent fabrication steps. Self-aligned metal silicide contacts 137 are separated from undesired regions using sidewall oxidation techniques.
Claims21
A method of fabricating a semiconductor structure in a silicon layer having an upper surface and having a first region of first conductivity type and second and third regions of second conductivity type, the first, second and third regions being separated at the surface from each other by field regions of insulating material inset into the layer, the method comprising:
- forming an insulating layer over the surface of the silicon layer,
- forming a protective layer of conductive material over all of the insulating layer except a first portion of the third region;
- introducing first conductivity type impurity into the first portion of the third region;
- using the protective layer as a mask removing the insulating layer from the surface of the silicon layer in the first portion of the third region;
- depositing additional conductive material over at least the first portion of the third region;
- removing the protective layer from the insulating layer except a first portion of the first region, a first portion of the second region and a second portion of the third region, the first portion of each of the first and second regions being spaced apart from the field regions;
- and
- introducing first conductivity type impurity into the second region except where overlaid by the protective layer, and second conductivity type impurity into the first region except where overlaid by the protective layer wherein an NMOS device is formed in the first region, a PMOS device is formed in the second region, and a bipolar device is formed in the third region.
A method of fabricating a semiconductor structure in a silicon layer having an upper surface and having a first region of first conductivity type and second and third regions of second conductivity type, the first, second and third regions being separated at the surface from each other by field regions of silicon dioxide inset into the layer, the method comprising:
- forming a gate insulating layer of silicon dioxide over the surface of the silicon layer;
- forming a layer of polycrystalline silicon over all of the gate insulating layer except a first portion of the third region where a base of a bipolar transistor is desired;
- introducing first conductivity type impurity into the first portion of the third region to define the base;
- using the polycrystalline silicon as a mask removing the gate insulating layer from the surface of the silicon layer in the first portion of the third region;
- depositing additional polycrystalline silicon over the first portion of the third region and over the layer of polycrystalline silicon;
- removing the polycrystalline silicon from the insulating layer except a first portion of the first region to define a gate electrode, a first portion of the second region to define another gate electrode and a second portion of the third region to define an emitter contact, the gate electrodes of each of the first and second regions being spaced apart from the field regions;
- and
- introducing first conductivity type impurity into the second region except where overlaid by the protective layer to define a source and a drain, and second conductivity type impurity into the first region except where overlaid by the protective layer to define another source and drain.
Dependencies are inferred from the claim text.